#include <iostream>
#include <cstring>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <set>
#include <bitset>
#include <utility>
using namespace std;

#define mm(a, n) memset(a, n, sizeof a)
#define mk(a, b) make_pair(a, b)

const double eps = 1e-4;
const int INF = 0x3f3f3f3f;

typedef long long LL;
typedef unsigned long long ULL;
typedef pair<int, int> PII;
typedef pair<double, double> PDD;
typedef pair<LL, LL> PLL;
typedef pair<int, LL> PIL;

inline void quickread()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
}

const double pi = acos(-1.0);

struct Point
{
    double x, y;
};

double dist(Point p1, Point p2)
{
    return sqrt((p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y));
}

double Angle(double a, double b, double c)
{
    return acos((a * a + b * b - c * c) / (2 * a * b));
}

double gcd(double a, double b)
{
    if (b + eps > 0 && b - eps < 0)
        return a;
    if (a + eps > 0 && a - eps < 0)
        return b;
    return gcd(b, fmod(a, b));
}

inline void solution()
{
    Point p1, p2, p3;
    while (~scanf("%lf%lf%lf%lf%lf%lf", &p1.x, &p1.y, &p2.x, &p2.y, &p3.x, &p3.y))
    {
        double a, b, c, p, s, r;
        double angle1, angle2, angle3;
        a = dist(p1, p2), b = dist(p1, p3), c = dist(p2, p3);
        p = (a + b + c) / 2;
        s = sqrt(p * (p - a) * (p - b) * (p - c));
        r = (a * b * c) / (4 * s);
        angle1 = Angle(r, r, a);
        angle2 = Angle(r, r, b);
        angle3 = 2 * pi - angle1 - angle2;
        double angle = gcd(angle1, gcd(angle2, angle3));
        double ans;
        ans = 0.5 * r * r * sin(angle) * ((2 * pi) / angle);
        printf("%.6lf\n", ans);
    }
}

int main()
{
    // freopen("input.txt", "r", stdin);
    quickread();
    solution();
    return 0;
}
